On Wed, Jun 14, 2017 at 12:57:25PM +0530, Sricharan R wrote:

Hi Varada,

On 6/14/2017 11:22 AM, Varadarajan Narayanan wrote:

quoted

It's possible for a SPI transaction to complete and get another
interrupt and have it processed on the same spi_transfer before the
transfer_one can set it to NULL.

This masks unexpected interrupts, so let's set the spi_transfer to
NULL in the interrupt once the transaction is done. So we can
properly detect these bad interrupts and print warning messages.

Signed-off-by: Matthew McClintock <redacted>
Signed-off-by: Varadarajan Narayanan <redacted>
---
 drivers/spi/spi-qup.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index bd53e82..1a2a9d9 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c

@@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 	struct spi_qup *controller = dev_id;
 	struct spi_transfer *xfer;
 	u32 opflags, qup_err, spi_err;
-	unsigned long flags;
 	int error = 0;
+	bool done = 0;
 
-	spin_lock_irqsave(&controller->lock, flags);
+	spin_lock(&controller->lock);
 	xfer = controller->xfer;
 	controller->xfer = NULL;
-	spin_unlock_irqrestore(&controller->lock, flags);
+	spin_unlock(&controller->lock);

 Why change the locking here ?

quoted

 
 	qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
 	spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);

@@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 			spi_qup_write(controller, xfer);
 	}
 
-	spin_lock_irqsave(&controller->lock, flags);
-	controller->error = error;
-	controller->xfer = xfer;
-	spin_unlock_irqrestore(&controller->lock, flags);
-
 	/* re-read opflags as flags may have changed due to actions above */
 	opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
 
 	if ((controller->rx_bytes == xfer->len &&
 		(opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
+		done = true;
+
+	spin_lock(&controller->lock);
+	controller->error = error;
+	controller->xfer = done ? NULL : xfer;
+	spin_unlock(&controller->lock);
+
+	if (done)
 		complete(&controller->done);
 

  Its not clear, why the driver is setting the controller->xfer = NULL
  and restoring it inside the irq. This patch seems to fix things on
  top of that.

I think the original intent was to make sure that the irqhandler knew that there
was no outstanding transaction.  This begs the question of why that would ever
be necessary.  I think it would suffice to rework all of that to remove that
behavior and perhaps enable/disable the irq as we need to during transactions.

I've never been a fan of the controller->xfer being set to NULL.


Regards,

Andy